1. Field of the Invention.
The present invention relates to RF receivers generally and, more particularly, but not by way of limitation, to novel means for extending the range of RF receivers.
2. Background Art.
While the present invention is described as applied to remote keyless entry RF receivers for vehicles, it will be understood that it is applicable, as well, to extending the receiving range of any RF receiver.
RF control devices used to lock/unlock vehicle doors and other similar types of RF control devices are beginning to be used extensively on vehicles. A problem being experienced with such devices is poor range, due to the power restrictions established by the Federal Communications Commission (FCC) on these low-range RF control devices. This restriction greatly limits the range to approximately 10 meters from the vehicle. Since the power is so low, the devices are constantly operating in the fringe area of their operating range. Therefore, any technique that can be used to extend the range of these devices without increasing the transmitted radiated signal would be desirable.
To increase the range of RF control devices, one could increase the transmitted radiated signal from the transmitter. This, as noted above, is limited by the FCC and most units are already designed to transmit the maximum allowable signal. Likewise, an improvement in receiver sensitivity may improve range, but such improvement may be very costly. In addition, receiver designs using today's technology are already designed to be close to the theoretical maximum sensitivity level. Another technique is to improve the receiving antenna design in some way to capture more of the available signal. However, using an external antenna on the receiver to pick up more of the transmitted signal may not be practical in some cases because of cost, space, or mechanical limitations.
Accordingly, it is a principal object of the present invention to provide an RF receiver range extender that avoids the use of an external antenna.
It is a further object of the invention to provide such range extender that does not require modification to the RF receiver.
It is an additional object of the invention to provide such range extender that is simple and economical.
It is another object of the invention to provide such range extender that can be retrofitted to existing RF receiver installations.
A further object of the invention is to provide such range extender that does not require FCC approval.
Other objects of the present invention, as well as particular features, elements, and advantages thereof, will be elucidated in, or be apparent from, the following description and the accompanying drawing figures.